![]() Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is particularly useful for direct identification of causative agents of bacteremia, which can be inducers of sepsis, within the same day of a positive blood culture (BC) broth result ( Schubert et al., 2011 Wuppenhorst et al., 2012 Chen et al., 2013 Clerc et al., 2013). Empirical treatment must be administrated at the time of sepsis diagnosis, and the regimen should be adjusted if necessary when bacterial identification and drug susceptibility results are available ( Kang et al., 2005 Dellinger et al., 2008 Kumar, 2011). Proper initial antibiotic therapy is a crucial parameter for improvement of patient outcomes ( Kumar et al., 2006 Dellinger et al., 2008). Sepsis is a major cause of infectious disease-associated morbidity and mortality ( Fleischmann et al., 2016). Adjustment of the logRQ cut-off value to 0.2 significantly increased the detection sensitivities for clinically important drug-resistant pathogens. The MBT STAR-BL test enabled the reporting of β-lactamase-producing GNR at 14.16 and 47.64 h before the interim and final reports of routine BCs processing, respectively, were available.Ĭonclusion: The MALDI Biotyper system equipped with the MBT STAR-BL module enables the simultaneous rapid identification of bacterial species and β-lactamase-mediated resistance from BCs and cultured isolates. Reducing the logRQ cut-off value from 0.4 to 0.2 increased the direct detection sensitivities for β-lactamase activities against ampicillin, cefotaxime and meropenem in BCs to 85.7, 87.5, and 100% respectively. ![]() Furthermore, the MBT STAR-BL and conventional drug susceptibility test results were concordant in 14/19 (73.7%) polymicrobial cultures. The overall specificities ranged from 91.5 to 100%. The detection sensitivities for β-lactamase activities against ampicillin, piperacillin, third-generation cephalosporin and meropenem were 91.3, 100, 97.9, and 100% for cultured isolates, and 80.4, 100, 68.8, and 40% for monomicrobial BCs ( n = 134) respectively. Results: Using the saponin-based extraction method, MALDI-TOF MS correctly identified bacteria in 116/134 (86.6%) monomicrobial BCs. All strains were also characterized by beta-lactamase PCR and sequencing. The results and turnaround times were compared with those of routine microbiological processing. Methods: Two hundred retrospective cultured isolates and 153 prospective BCs containing Gram-negative rods (GNR) were collected and subjected to direct bacterial identification, followed by the measurement of β-lactamase activities against ampicillin, piperacillin, cefotaxime, ceftazidime, and meropenem using the MBT STAR-BL module. Objective: This study evaluated the capability of a MALDI Biotyper system equipped with the newly introduced MBT STAR-BL module to simultaneously perform species identification and β-lactamase-mediated resistance detection in bacteremia -causing bacteria isolated from cultured isolates and patient-derived blood cultures (BCs). ![]()
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